It is often desirable, and sometimes necessary, to know the location of a terminal, e.g., a cellular phone. The terms “location” and “position” are synonymous and are used interchangeably herein. For example, a location services (LCS) client may desire to know the location of the terminal. The terminal (e.g. a User Equipment (UE), a Mobile Station (MS), a Secure User Plane (SUPL) Enabled Terminal (SET), etc.) may then communicate with a location server to obtain a location estimate for the terminal. The terminal or the location server may then return the location estimate to the LCS client.
A message flow (which may also be referred to as a call flow or a procedure) may be executed to establish a location session whenever the LCS client desires to know the location of the terminal. Various messages may be exchanged between the terminal and the location server via one or more network entities for the message flow. These messages may conform to a positioning protocol such as the Long Term Evolution Positioning Protocol (LPP) defined by the 3rd Generation Partnership Project (3GPP) or the LPP Extensions (LPPe) protocol being defined by the Open Mobile Alliance (OMA). The messages may transfer assistance data from the location server to the terminal to assist the terminal to obtain location related measurements (e.g. measurements of signals from GPS satellites) and/or to compute a location estimate from these measurements. The messages may also transfer location information (e.g. measurements or a location estimate) from the terminal to the location server to enable the location server to determine the location of the terminal.
Some positioning protocols such as LPPe may allow large amounts of location assistance data to be transferred from a location server to a terminal. One example would be long term satellite orbital data for multiple Global Navigation Satellite Systems (GNSSs). Another example would be map data for a particular area, region or building structure that could be used by a terminal to help determine its location and/or make use of its location once determined. The size of such assistance data may be significant—e.g. a few hundred kilobytes or even 1 Mbyte or more. Transferring such a large amount of data in a single message or even in a sequence of separate messages could congest the server or terminal and interfere with other activities being performed by the server, terminal and serving access network. In addition, there is a risk that the connection or location session between the server and terminal could fail or be released before all the assistance data has been transferred. In that case, the complete transfer might need to be restarted at a later time.